Barbecue grill humidifier



FIG. 1 is a top perspective view of a barbecue grill humidifier showing our new design;

FIG. 2 is a right side elevational view thereof, the left side being a mirror image thereof;

FIG. 3 is a top plan view thereof; and,

FIG. 4 is an end elevational view thereof, the other end being a mirror image thereof.

The bottom of the barbecue grill humidifier is unornamented and is not part of the claimed design. 

The ornamental design for a barbecue grill humidifier, as shown and described. 